Colleges and universities in the U.S. are a prime target for hackers, who are outstripping efforts to prevent, or even detect, their cyber attacks, experts tell the New York Times (reg. req.)

“We get 90,000 to 100,000 attempts per day, from China alone, to penetrate our system,” said Bill Mellon, the associate dean for research policy at the University of Wisconsin. “There are also a lot from Russia, and recently a lot from Vietnam, but it’s primarily China.”

Although the nation’s educational institutions don’t want to eliminate their teaching mission by creating impenetrable virtual walls around their computer systems, many are imposing new security measures, such as a rule against taking a laptop computer to certain countries.

“There are some countries, including China, where the minute you connect to a network, everything will be copied, or something will be planted on your computer in hopes that you’ll take that computer back home and connect to your home network, and then they’re in there,” senior fellow James A. Lewis of the Center for Strategic and International Studies told the newspaper. “Academics aren’t used to thinking that way.”